Improvements in Surface Tension Measurements of Liquid Metals Having Low Capillary Constants by the Constrained Drop Method

Surface tension of liquid alloys can be estimated by thermodynamic calculations. In the calculations, reliable reference data of the surface tension of the respective pure metal components of the liquid alloy system and its temperature dependence are important. One of the most popular methods in surface tension measurements is the sessile drop method. Recently, from simulations based on Laplace equation, the authors showed that more reliable surface tension values could be obtained as the drop size increases, because the contour of the drop profile is distinguishable clearly to that of slightly changed surface tensions by 10%. The simulated results were confirmed with measurements of the surface tension of liquid metals having low melting temperatures such as Ga, Sn, Bi, In and Pb by using the constrained drop method with a large axi-symmetric drop in a special crucible as shown in Fig. 1(a). In Fig. 2, the surface tension measurements of liquid Sn with changing the size of liquid metal drop were plotted as a function of temperature. In order to increase the size of the drop, various crucibles of different sizes (6 mm, 8 mm and 10 mm in diameter) were adopted. The deviation of the surISIJ International, Vol. 44 (2004), No. 11, pp. 1793–1799